基于覆膜砂激光快速成型的无模快速铸造方法研究

用激光扫描覆膜砂,当激光功率足够大时,覆膜砂的树脂膜会发生过烧和炭化而失去粘结作用。利用此特点,本文提出一种以激光扫描零件轮廓边界为基础的直接生成铸型的方法:用大功率激光逐层扫描出零件各层的轮廓边,相当于在覆膜砂上扫描出目标模型与砂型的分割面,对砂箱整体进行加热固化后,可得到三维的目标模型和砂型。本文给出了由此方法实现快速铸造的工艺方案,并进一步实现了金属零件的快速铸造。该方法有别于SLS工艺的面域扫描,具有分层简单、成型时间短、速度快、成型件强度高的特点,实现了铸造零件CAD/CAM的计算机集成制造,对缩短新产品开发周期和降低成本具有重要的意义。

Research on Pattern-Less Quick Casting Based on Laser Rapid Prototyping for Coated Sand

The resin films of coated sand will be overheated and carbonized while the coated sand is scanned by the laser with a high enough power,and thus lose the binding effect.By using this feature,a method of direct mold making based on part contour scanning by laser was introduced-The part contour is scanned layer by layer with a high enough power laser,so a parting surface which separate the object model from the sand mould will be formed.Then the object model and the sand mould will be obtained after heating the whole sand box.A process chart for quick casting based on this method was presented,and a metal part was produced.This method differs from the region scanning of SLS,characterizes by simple slicing,rapid prototyping and high strength,and achieves the computer integrated manufacture of casting CAD/CAM.It is meaningful to shorten the cycle and reduce the cost of new products development.